This coloration on the Lightning has come to be called the "Emerald Green" Lightning.  To me, it isn't emerald green.  The definition of "emerald green" is the emerald green Flaccus and this one isn't even close.  This is what I would term a Green Teal but apparently, I'm the only one in the hobby who would name it that so, for historical reasons if nothing else, this remains the "emerald lightning".  I have to admit that it's got a painted lid.  There are no "emerald" lids and this one came with the painted lid from the Alex Kerr collection so I leave it that way.

Whatever color it is, its beautiful and very rare.